1. Field of the Invention
The present invention relates to a device for intermittently feeding a thin-web frame at a predetermined pitch.
2. Description of the Related Art
FIGS. 4 and 5 show a known device for feeding a thin-web frame used in a die apparatus. More specifically, FIG. 4 is a top plan view of the die apparatus with an upper die member thereof removed, while FIG. 5 is a side elevational view of the die apparatus. Referring to these Figures, a thin-web frame 1 is fed by a feeding device 2 along a guide rail 4 intermittently at a predetermined pitch. The feeding device 2 has a feeding shaft 22 to which a pair of feed arms 21 are fixed at a predetermined spacing from each other. Each arm 21 has a pair of pins 21a for engaging locating holes 1a formed in the thin-web frame 1. The feeding shaft 22 is connected to a driving unit 23 which has, for example, a hydraulic cylinder, slidingly driven in the directions of arrows Q-P. A grooved plate 24 has a groove which receives a roller 25 provided on one end of one of the arms 21 such that the roller 25 can roll back and forth in the directions of arrows Q-P. The grooved plate 24 is held stationary. The die apparatus has lower and upper die members 31 and 32 which cooperate with each other in deforming the thin-web frame 1 into a desired configuration and four guide posts 33 secured to the lower die member 31 and for guiding the upper die member 32 in alignment with the lower die member 31 when the upper die member 32 is moved up and down by operation of a press machine 5. The upper die member 32 is provided with a projection 32a which engages the guide rail 4 to move it downward when the upper die member 32 is lowered by the press machine 5. A compression spring (not shown) is loaded to act on the underside of a portion of the guide rail 4 projecting outward from the die apparatus 3 so that the guide rail 4 is floated above the lower die member 31 as illustrated.
In operation, the upper die member 32 is lifted by the press machine 5 up to top dead center. As a consequence, the guide rail 4 is floated by the resetting force produced by the compression spring (not shown), so that the pins 21a on the feed arms 21, which have been stationed in alignment with the locating holes 1a in the thin-web frame 1, are inserted into these locating holes 1a. Subsequently, the driving unit 23 drives the feeding shaft 22 in the direction of the arrow P. As a result, the feed arm 21 fixed to the feeding shaft 22 are moved in the same direction and by the same distance as the feeding shaft 22 while being held in a horizontal position by cooperation between the roller 25 and the grooved plate 24, whereby the thin-web frame 1 is fed by a predetermined distance in the direction of the arrow A. Then, the press machine 5 commences its downward stroking so as to push the upper die member 32 downward so that the upper die member 32 moved downward along the guide posts 33. At the same time, the guide rail 4 is pushed downward by the projection 32a of the upper die member 32 so as to move downward by a predetermined distance. Consequently, the thin-web frame 1 is pressed against the lower die member 31 and, when the press machine 5 completes its downward stroke to the bottom dead center, the portion of the thin-web frame 1 pressed between the lower and upper die members 31, 32 is plastically deformed into a predetermined configuration. The press machine then commences upward stroking operation to lift the upper die member 32. While the guide rail 4 is in the lowered state, the feeding shaft 22 has been returned by the driving unit 23 in the direction of the arrow Q so that the feed arms 21 have been reset to the initial positions. The above-described operation is then repeated to feed the thin-web frame 1 intermittently, thereby conducting the press work over the whole length of the thin-web frame 1.
Thus, the known feeding device for feeding thin-web frame feeds the thin-web frame by means of pins on the feed arms engaging locating holes formed in the thin-web frame. It is therefore necessary to change feed arms or the whole feeding device in accordance with the types of the thin-web frame conveyed. Another problem is that, since the die apparatus, feeding device and the external driving unit for driving the feeding device are constructed separately and the feeding device is drivingly connected to the driving unit through the feeding shaft, change of die members in accordance with a change in the type of the press work requires changing or re-combining the feeding device, requiring an impractically long time.